Reinforced concrete structures are frequently subjected to both high- and low-cycle fatigue loadings, due to, for instance, traffic or earthquake, which may lead to significant losses or even catastrophic disasters. Carbon fiber-reinforced polymer (CFRP) composites have been frequently used to increase the fatigue life of existing concrete structures. However, the debonding of the CFRP reinforcement still represents one of the most dangerous failure mechanisms, which should be avoided by a proper design. At the interface between FRP and concrete, cyclic loading may induce the accumulation of inelastic deformations and lead to the formation of micro-cracks and crack coalescence resulting in interface debonding. This occurs for stress levels smaller than those causing debonding under quasi-static monotonic loading. This paper reports the results of an experimental investigation into the static and fatigue behavior of the interfacial bond between a CFRP composite and a concrete substrate, considering the effect of the load frequency. Single-lap direct shear tests with a constant bonded length under four load frequencies were performed. Fatigue and post-fatigue loading curves, modes of failure, and fatigue lives were obtained to investigate the effect of the load frequency on the specimen response.